Potentialities of cellulose nanofibers (CNFs) in low density polyethylene (LDPE) composites

The growing demand for polymeric materials has made them significant in both industry and the environment, and the task of making them sustainable is becoming increasingly challenging. Cellulose presents an opportunity to minimize the effect of nondegradable materials. Cellulose nanofibers (CNFs) are a class of cellulose fibers with superior performance due to their high strength and stiffness combined with low weight and biodegradability. This work aimed to produce composites using low-density polyethylene (LDPE) as a matrix and CNFs from Pinus sp. (Pinus) and Eucalyptus sp. (Eucalyptus) as reinforcements. The CNFs were obtained by mechanical defibrillation of the cellulose, and subsequently, the water was removed by centrifugation to produce a master with CNFs and LDPE using a thermokinetic homogenizer. The master was milled and blended with LDPE to obtain booster concentrations of 1, 2 and 3% by weight (wt%). To characterize the composites, tensile and flexural tests and thermal and rheological analyses were performed. An increase of between 3 and 4% in the crystallinity of the composite was observed with the addition of Pinus CNF, and a decrease of 2 to 3% in the crystallinity index was observed with the addition of Eucalyptus CNF. The thermal stability increased for all the compositions. For the mechanical properties, increasing the CNF content increased the stiffness and tensile strength. In general, this process is an effective alternative for producing composites of LDPE with cellulose nanofibers.